This invention relates to tubular probes and devices for delivering said probes into body cavities. Such probes most prevalently find use as catheters and specifically, urinary catheters which are used for a variety of medical reasons such as to drain the bladder of accumulated urine, to introduce medication, to lavage, to correct physiological defects and to ascertain urinary output.
The commonly used catheter consists of a simple single-walled tube or, in the case of a retention catheter, a single-walled tube along side a second tube through which a fluid is provided for inflating a retention balloon, this latter type known generally as a Foley catheter. These catheters are emplaced by sliding the same into a body passage in a process which is both difficult for the doctor and painful for the patient. Recently, it has been discovered that a new form of urinary catheter may be inserted by the method of "eversion", obviating the sliding method of insertion and greatly facilitating the emplacement process. As applied to this instant invention, the eversion method is utilized in a device wherein a tube is placed in a pressurizing chamber having an opening at one end. One end of the tube is sealed across this opening. In operation, the chamber is pressurized with a fluid such as water, the pressurizing fluid exerts a force across the opening of the chamber and pushes the tube out of the chamber and into the body cavity. Because one end of the tube is fixed across the opening of the chamber, the tube is forced out of the chamber in a double-walled configuration wherein the annulus is filled with pressurizing fluid and the center, void of such fluid, provides a conduit for the usual catheter purposes.
While this eversible probe greatly alleviates the discomfort and difficulties concomitant with medical procedures such as catheterization, the device is considerably more complex than the simple catheters used heretofore and such complexity generates drawbacks. One particularly difficult problem associated with the use and design of these eversible catheters is the difficulty in sealing the pressurized annulus after the probe has been completely everted. At that point in time, it is desirable to remove the pressurizing chamber from the tubing and at the same time, maintain a sealed annulus. Another problem is that, as with present urinary catheter systems, as soon as the probe penetrates the sphincter muscle and enters the trigone area of the bladder, there is an immediate flow of urine into the conduit. Thus, it is necessary to provide a sealing means to preclude uncontrolled flow of urine at this point in time. Because of the complex nature of the eversible catheter, no truly satisfactory method has heretofore been available for sealing the annulus and precluding the premature flow of urine.